1. The Field of the Invention
The present invention is directed generally to methods and apparatus for employing blood management during surgical procedures. More specifically, the present invention is directed to methods and apparatus for employing blood management during cardiac surgical procedures wherein cardiac arrest is induced and extracorporeal circulation and venting of the heart are provided.
2. Related Application
Benefit of the earlier filing date of Provisional Patent Application Ser. No. 60/025,503, filed Sep. 5, 1996, is claimed for this application under Section 119(e) of Title 35 of the United States Code.
3. The Relevant Technology
During surgical procedures involving the heart, it is often beneficial or necessary to provide life support, a bloodless surgical field, and a flaccid heart. Generally speaking, the procedure by which these are accomplished is known as cardiopulmonary bypass. Conventionally, in order to access the heart to initiate cardiopulmonary bypass, a surgeon first exposed the thoracic cavity via a central incision down the breastbone in a procedure known as a "median sternotomy," and dissected away tissue overlying the heart. A significant interest has developed in decreasing the extent of invasiveness necessary to perform cardiopulmonary bypass, with the intent to increase the effectiveness and success of the procedure.
For example, U.S. Pat. No. 5,478,309 by Sweezer et al., (hereinafter Sweezer et al.), discloses an approach for achieving total cardiopulmonary bypass during heart surgery utilizing a two catheter system without the need for a median sternotomy. A venous perfusion catheter is inserted peripherally into the atrial-caval junction, with two balloons blocking the flow of blood into the right atrium. This catheter provides the venous return to the cardiopulmonary bypass machine. An arterial perfusion catheter is inserted peripherally into the ascending aorta just above the coronary artery junction and provides aortic occlusion, aortic root venting, left ventricular decompression, aortic root cardioplegia delivery, and delivery of oxygenized arterial blood. However, in order to accommodate its multiplicity of functions, the arterial perfusion catheter must be substantially enlarged.
Similarly, U.S. Pat. No. 5,433,700 by Peters, (hereinafter Peters), discloses a process for inducing cardioplegic arrest and maintaining peripheral cardiopulmonary bypass utilizing only two catheters. This process positions a catheter into the right atrium via insertion through a femoral vein. This catheter employs two inflatable cuffs to allow isolation of the right atrium, and provides venous return to the cardiopulmonary bypass machine. The process additionally positions a catheter in the ascending aorta via insertion through a femoral artery. The arterial catheter occludes the ascending aorta, introduces cardioplegia, vents the left heart, and delivers oxygenated blood into arterial circulation. Yet, as in Sweezer et al., the Peters approach requires a significantly enlarged arterial catheter for performing a multiplicity of functions.
Still another approach is disclosed in U.S. Pat. No. 5,558,644 by Boyd et al., (hereinafter Boyd et al.). Specifically, Boyd et al. discloses a system for inducing cardioplegic arrest and sustaining cardiopulmonary bypass comprising a retrograde delivery catheter for occluding the coronary sinus, a venous cannula for withdrawing blood from a peripheral vein, an elongated arterial catheter inserted through the femoral or brachial artery for occluding the ascending aorta, an arterial return cannula for whole body perfusion, and a catheter placed in the pulmonary artery for venting the left atrium. Essentially, Boyd et al. attempts to minimize invasiveness by using at least five separate catheters.
Although substantial effort has been expended in designing various systems that look promising for decreasing the extent of invasiveness necessary to perform cardiopulmonary bypass, none has proven effectively workable in practical application. Consequently, the desired improvements in the effectiveness and success of the procedures requiring cardiopulmonary bypass have not followed.